The U.S. military has been using video games to prepare soldiers for war for quite some time, and recently, it's also been using virtual reality systems as a way to reduce symptoms -- and even prevent combat soldiers from getting PTSD in the first place.

Scientists at USC are using the virtual reality systems as a kind of inoculation against the negative psychological effects of war - employing the virtual reality programs to prepare soldiers for the trauma they'll experience in war and to someday perhaps identify who may or may not be psychologically fit for combat.